Background- '99 Jimmy 95k on the clock. The cold weather has just hit and I've noticed two things.

One- oil pressure. Its normally been around 60psi at startup, then dropping to 20psi at warm idle and 45 while running. Recently, now that its getting cold, a few mornings I've noticed it start at 45psi at idle and peg at 80 psi between 2k RPM. Once it warms up, it tends to stay right at 45psi.

Around the same time, I've noticed a LOUD valve tick when cold that gradually goes away as the engine warms, usually going away totally within 3-4 minutes. This is with temps right around freezing outside.

Anyway, oil has 2k miles on Mobil1 5W30.

Is this normal cold weather behavior on these trucks?

Thanks,
Mike

 

A ticking noise from the valve train does not sound normal to me. I would install an oil pressure tester and verify the oil pressure first. If the pressure seems ok, then I would remove the valve cover (or covers), on the noisy side (or sides) and check for loose or worn rocker arms, worn rocker *****, or dry rockers.
Next would be plugged or bent push rods, worn lifters and finally a worm camshaft.

 

Make sure you have proper oil level.
Low on oil will cause ticking noise. Being cold the oil gets thicker, harder to flow, and also leads to ticking noise.

When the oil warms up, the ticking noise goes away.
Veryify you indeed do have 5w30 in there. Thicker oil is OK in the summer, you need thinner oil in the winter. Do an oil change.